Recovery of hepatocytes from attack by the pore former amphotericin B.

Sublytic amounts of the pore former Amphotericin B (AmB) induced transient movements of Na and K ions across the hepatocyte plasma membranes without altering the intracellular free Ca ion concentration. The presence of 1-5 microM-AmB induced leakage of up to 80% of the intracellular K+ within 3 min, followed by Na+ entry without loss of cell viability. A repair process occurred after 3-10 min, which restored the initial cationic concentrations. Progressive binding of AmB to the cells could be observed by following the disappearance of the intense excitonic dichroic doublet of free AmB. It was shown that the amount of AmB binding, responsible for the Na+ and K+ movements, was low (approx. 16% of total AmB). The recovery process occurred when higher amounts of AmB bound to the cells, and was mediated by Na+/K+-ATPase. The c.d. spectrum of AmB bound to isolated hepatocyte plasma membranes, indicated that during this step AmB formed a complex with cholesterol, similar to that formed by the binary mixture in water.